Question

我有一个名为test_database的数据库。我得到了一张名为tbl_marks的桌子。在tbl_marks中有以下行：

_id
名称
的子ID
gewicht
基准

有4个条目。两个带有子带1，另外两个带有子带2。

现在我想做以下事情：

SELECT * FROM tbl_marks WHERE subid = 1;

所以最后我想列出subid 1,2,3或列表视图中的所有标记。

我怎么能用光标做到这一点？

我试图通过教程学习它，但它失败了......

Higherpass Android Tutorial Accessing-Data-With-Android-Cursors

Anddev Working with the sqlite database - Cursors

代码：评论的部分是我之前得到的（它列出了所有内容）

private void fillData() {
    // Get all of the notes from the database and create the item list

    mDbHelper.open_database_rw();
    Cursor mCursor = db.rawQuery("SELECT _id, subid, name, mark, gewicht, datum FROM tbl_marks ORDER BY subid;", null);
    startManagingCursor(mCursor);
    if (mCursor != null) {
         int intName = mCursor.getColumnIndexOrThrow("subid");

          do {
              teststring = mCursor.getString(intName);

              String[] from = new String[] { dbHelper.KEY_NAME_MARKS, dbHelper.KEY_MARK_MARKS, dbHelper.KEY_GEWICHT_MARKS, dbHelper.KEY_DATUM_MARKS};
              int[] to = new int[] {R.id.txt_marks_row, R.id.txt_note, R.id.txt_gewicht, R.id.txt_datum};


              SimpleCursorAdapter notes = new SimpleCursorAdapter(this, R.layout.show_marks, mCursor, from, to);
              setListAdapter(notes);
          } while (mCursor.moveToNext());

    }

LogCat说列subid不存在。但它就在那里，数据库已经打开了。

02-07 11:30:00.500: D/dalvikvm(9913): GC_EXTERNAL_ALLOC freed 54K, 50% free 2694K/5379K, external 0K/0K, paused 56ms
02-07 11:30:00.535: D/dalvikvm(9913): GC_EXTERNAL_ALLOC freed 4K, 50% free 2698K/5379K, external 13K/523K, paused 27ms
02-07 11:30:10.457: D/AndroidRuntime(9913): Shutting down VM
02-07 11:30:10.457: W/dalvikvm(9913): threadid=1: thread exiting with uncaught exception (group=0x40235568)
02-07 11:30:10.457: E/AndroidRuntime(9913): FATAL EXCEPTION: main
02-07 11:30:10.457: E/AndroidRuntime(9913): java.lang.RuntimeException: Unable to start activity ComponentInfo{test.marco.notenha/test.marco.notenha.mark}: java.lang.IllegalArgumentException: column 'subid' does not exist
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1664)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1680)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.os.Handler.dispatchMessage(Handler.java:99)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.os.Looper.loop(Looper.java:130)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.app.ActivityThread.main(ActivityThread.java:3703)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at java.lang.reflect.Method.invokeNative(Native Method)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at java.lang.reflect.Method.invoke(Method.java:507)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at dalvik.system.NativeStart.main(Native Method)
02-07 11:30:10.457: E/AndroidRuntime(9913): Caused by: java.lang.IllegalArgumentException: column 'subid' does not exist
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:314)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at test.marco.notenha.mark.fillData(mark.java:180)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at test.marco.notenha.mark.onCreate(mark.java:70)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-07 11:30:10.457: E/AndroidRuntime(9913):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1628)
02-07 11:30:10.457: E/AndroidRuntime(9913):     ... 11 more

那是第180行：int intName = mCursor.getColumnIndexOrThrow（“subid”）;

02-07 11:52:26.304: D/dalvikvm(10075): GC_EXTERNAL_ALLOC freed 48K, 50% free 2694K/5379K, external 0K/0K, paused 38ms
02-07 11:52:26.339: D/dalvikvm(10075): GC_EXTERNAL_ALLOC freed 4K, 50% free 2698K/5379K, external 13K/523K, paused 30ms
02-07 11:52:29.433: D/AndroidRuntime(10075): Shutting down VM
02-07 11:52:29.433: W/dalvikvm(10075): threadid=1: thread exiting with uncaught exception (group=0x40235568)
02-07 11:52:29.437: E/AndroidRuntime(10075): FATAL EXCEPTION: main
02-07 11:52:29.437: E/AndroidRuntime(10075): java.lang.RuntimeException: Unable to start activity ComponentInfo{test.marco.notenha/test.marco.notenha.mark}: android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 3
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1664)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1680)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.os.Looper.loop(Looper.java:130)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.app.ActivityThread.main(ActivityThread.java:3703)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at java.lang.reflect.Method.invokeNative(Native Method)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at java.lang.reflect.Method.invoke(Method.java:507)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at dalvik.system.NativeStart.main(Native Method)
02-07 11:52:29.437: E/AndroidRuntime(10075): Caused by: android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 3
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.database.AbstractCursor.checkPosition(AbstractCursor.java:580)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:214)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:41)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at test.marco.notenha.mark.fillData(mark.java:183)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at test.marco.notenha.mark.onCreate(mark.java:70)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-07 11:52:29.437: E/AndroidRuntime(10075):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1628)
02-07 11:52:29.437: E/AndroidRuntime(10075):    ... 11 more

Answer 1

“subid”列必须位于SELECT列列表中，以便 mCursor.getColumnIndexOrThrow（“subid”）调用返回它：

SELECT _id, name, mark, gewicht, datum, subid FROM tbl_marks ORDER BY subid;

修改

现在你需要调用mCursor.moveToFirst（）并检查它是否返回“true”（即结果列表不为空）。见this question。举个例子：

if (mCursor != null && mCursor.moveToFirst()) { int intName = mCursor.getColumnIndexOrThrow("subid"); do { teststring = mCursor.getString(intName); ... } while (mCursor.moveToNext()); }

Answer 2

myDB = openOrCreateDatabase("tbl_marks", MODE_PRIVATE, null);


Cursor mCursor = myDB.rawQuery("SELECT _id, name FROM tbl_marks ORDER BY name;", null);
startManagingCursor(mCursor);
if (myCursor != null) {
     int intName = myCursor.getColumnIndexOrThrow("name");
     if(mCursor.moveToFirst()){
          String strName = myCursor.getString(intName);

     /* do {
          String strName = myCursor.getString(intName);
        } while (myCursor.moveToNext());*/ 

    }

}

如果你想在列表视图中显示结果：

myDB = openOrCreateDatabase("tbl_marks", MODE_PRIVATE, null);


Cursor mCursor = myDB.rawQuery("SELECT name, mark, gewicht, datum FROM tbl_marks ORDER BY subid;", null);
startManagingCursor(mCursor);
if(mCursor.moveToFirst()){
    ListView lv = (ListView)findViewById(R.id.listview);
    ListAdapter adapter = new SimpleCursorAdapter(
                        this, // Context.
                        android.R.layout.simple_list_item_1,
                        mCursor,
                        new String[] {"name"},
                        new int[] {android.R.id.text1});

    lv.setAdapter(adapter);
}

Answer 3

您可以使用此查询

SELECT * FROM tbl_marks order by subid

然后通过使用光标，您可以检索所需的记录。

如何从SQLite表中读取多行的多条记录？

3 个答案: